CAN COMMUNICATION SYSTEM Main Body ECU Communication Stop Mode

DESCRIPTION

Detection Item Symptom Trouble Area
Main Body ECU Communication Stop Mode

Either condition is met:


  • "Main Body" is not displayed on the "CAN Bus Check" screen Click here.

  • Communication system DTCs (DTCs that start with U) that are output correspond to "Main Body ECU Communication Stop Mode" in "DTC Combination Table" Click here.

  • Main body ECU (instrument panel junction block assembly) CAN branch wire or connector

  • Power source circuit of main body ECU (instrument panel junction block assembly)

  • Main body ECU (instrument panel junction block assembly) ground circuit

  • Main body ECU (instrument panel junction block assembly)

WIRING DIAGRAM

A002MLKE02

CAUTION / NOTICE / HINT

Note


  • Because the order of diagnosis is important to allow correct diagnosis, make sure to begin troubleshooting using How to Proceed with Troubleshooting when CAN communication system related DTCs are output Click here.

  • Before measuring the resistance of the CAN bus, turn the ignition switch off and leave the vehicle for 1 minute or more without operating the key, switches or opening or closing the doors. After that, disconnect the cable from the negative (-) battery terminal and leave the vehicle for 1 minute or more before measuring the resistance.

  • After turning the ignition switch off, waiting time may be required before disconnecting the cable from the battery terminal. Therefore, make sure to read the disconnecting the cable from the battery terminal notice before proceeding with work Click here.

  • Inspect the fuses for circuits related to this system before performing the following inspection procedure.

  • After performing repairs, perform the DTC check procedure and confirm that the DTCs are not output again.

  • After the repair, perform CAN Bus Check and check that all the ECUs and sensors connected to the CAN communication system are displayed Click here.

Tech Tips


  • Operating the ignition switch, any switches or any doors triggers related ECU and sensor communication with the CAN, which causes resistance variation.

  • Even after DTCs are cleared, if a DTC is stored again after driving the vehicle for a while, the malfunction may be occurring due to vibration of the vehicle. In such a case, wiggling the ECUs or wire harness while performing the inspection below may help determine the cause of the malfunction.

PROCEDURE


  1. CHECK FOR OPEN IN CAN BUS WIRE (MAIN BODY ECU CAN BRANCH WIRE)


    1. A002LJIE02
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Main Body ECU [Instrument Panel Junction Block Assembly])

      Disconnect the cable from the negative (-) battery terminal.

    2. Disconnect the main body ECU (instrument panel junction block assembly) connector.

    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      Tester Connection Condition Specified Condition
      H81-15 (CANH) - H81-16 (CANL) Cable disconnected from negative (-) battery terminal 54 to 69 Ω
      Result
      Result Proceed to
      OK (w/o Stop and Start System) A
      OK (w/ Stop and Start System) B
      NG C

    B

    CHECK HARNESS AND CONNECTOR (MAIN BODY ECU - BATTERY AND BODY GROUND) Click here

    C

    REPAIR OR REPLACE CAN BRANCH WIRE CONNECTED TO MAIN BODY ECU (CANH, CANL)

    A

  2. CHECK HARNESS AND CONNECTOR (MAIN BODY ECU - BATTERY AND BODY GROUND)


    1. Connect the cable to the negative (-) battery terminal.

      A002O57E02
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Main Body ECU [Instrument Panel Junction Block Assembly])

      		 - -

      Note

      When disconnecting the cable, some systems need to be initialized after the cable is reconnected Click here.

    2. Disconnect the main body ECU (instrument panel junction block assembly) connectors.

    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      Tester Connection Condition Specified Condition
      DE-28 (GND1) - Body ground Always Below 1 Ω
      H80-4 (GND2) - Body ground Always Below 1 Ω

    4. Measure the voltage according to the value(s) in the table below.

      Standard Voltage
      Tester Connection Condition Specified Condition
      DH-12 (BECU) - Body ground Always 11 to 14 V
      DG-1 - Body ground Always 11 to 14 V
      DF-3 (IG) - Body ground Ignition switch ON 11 to 14 V
      DF-5 (ACC) - Body ground Ignition switch ACC 11 to 14 V

    OK

    REPLACE MAIN BODY ECU (INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY)

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

  3. CHECK HARNESS AND CONNECTOR (MAIN BODY ECU - BATTERY AND BODY GROUND)


    1. Connect the cable to the negative (-) battery terminal.

      A002LLXE02
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Main Body ECU [Instrument Panel Junction Block Assembly])

      		 - -

      Note

      When disconnecting the cable, some systems need to be initialized after the cable is reconnected Click here.

    2. Disconnect the main body ECU (instrument panel junction block assembly) connectors.

    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      Tester Connection Condition Specified Condition
      DE-28 (GND1) - Body ground Always Below 1 Ω
      H80-4 (GND2) - Body ground Always Below 1 Ω

    4. Measure the voltage according to the value(s) in the table below.

      Standard Voltage
      Tester Connection Condition Specified Condition
      DH-12 (BECU) - Body ground Always 11 to 14 V
      DH-13 (IG) - Body ground Ignition switch ON 10.5 to 16 V
      DF-5 (ACC) - Body ground Ignition switch ACC 11 to 14 V
      Result
      Result Proceed to
      OK A
      NG (IG terminal) B
      NG (Except IG terminal) C

    A

    REPLACE MAIN BODY ECU (INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY)

    B

    GO TO STOP AND START SYSTEM Click here

    C

    REPLACE MAIN BODY ECU (INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY)